The relation between plasma thrombopoietin and erythropoietin concentrations in polycythaemia vera and essential thrombocythaemia

Oxygen affinity is decreased in patients with polycythaemia vera and essential thrombocythaemia

The plasma erythropoietin (EPO) concentration is subnormal in the vast majority of all patients at the time of diagnosis of polycythaemia vera (PV) and in 33-50% of patients with essential thrombocythaemia (ET). At equivalent haemoglobin concentrations patients with PV and a substantial number of ET patients have subnormal EPO concentrations compared with those of healthy subjects. A possible explanation could be altered haemoglobin (Hb) oxygen affinity. Plasma EPO concentration and the oxygen pressure at 50% Hb saturation (p50) were measured in 29 patients with PV, 23 patients with ET and 34 healthy controls. There was no significant correlation between p50 and plasma EPO concentration. However, the mean p50 for PV patients exceeded the mean for healthy controls (p = 0.004). Furthermore, the mean p50 for ET patients significantly (p = 0.012) exceeded the mean for controls but there was no significant difference in p50 between patients with PV and ET. It could be hypothesized that the lower oxygen affinity to Hb in PV and ET patients partly explains the decreased EPO production.

TPO, but not soluble-IL-6 receptor, levels increase after anagrelide treatment of thrombocythemia in chronic myeloproliferative disorders

Anagrelide is often used in the treatment of thrombocythemia in myeloproliferative disease (MPD), but information concerning effects of treatment on cytokines involved in regulation of blood platelet levels is limited. Here, we investigated serum levels of thrombopoietin (TPO) and soluble IL-6 receptor (sIL-6R) in relation to response to treatment with and plasma concentrations of anagrelide. Samples from 45 patients with thrombocythemia due to MPD (ET=31, PV=14), being treated with anagrelide for 6 months, were analyzed for TPO, sIL-6R and anagrelide levels. The mean baseline platelet count was 983x10(9)/L. A reduction of platelets to <600 in asymptomatic or <400 x 10(9)/L in symptomatic patients was defined as a complete remission (CR), a reduction with >50% of baseline as partial remission, and <50% reduction as failure. At 6 months, 35 patients were in CR, 1 had a partial remission and 9 were treatment failures. For all patients, there was an increase in TPO of 44% from baseline; this change was more pronounced for patients with partial remission and failure. sIL-6R levels did not change significantly. There was no correlation between levels of anagrelide and cytokine levels at 6 months, and changes of cytokine levels did not relate to changes of platelet counts. Thus, a pronounced increase of TPO levels after 6 months of anagrelide treatment indicated that this treatment affected a major regulatory mechanism for megakaryocyte and platelet formation in MPD.

Coexistence of chronic lymphocytic leukemia and essential thrombocythemia

The association of chronic lymphocytic leukemia (CLL) with essential thrombocythemia (ET) is an extremely rare event and until now 3 patients with such coexistence have been reported in the literature. We report a 77-year-old white woman in whom these two disorders were diagnosed concomitantly on the basis of peripheral blood count and cytology, bone marrow cytology and histology, immunophenotyping, as well as exclusion criteria. The diagnosis of ET was also supported by spontaneous in-vitro erythroid colony growth and by evaluation of thrombopoietin (TPO) serum level. Interphase FISH analysis allowed to detect 13q14.3 deletion in 98% of lymphocytes nuclei. In contrast this aberration was not observed in the megakaryocytes. The results of PCR analysis of IgG gene rearrangement showed distinct bands characteristic for monoclonal lymphoid population in bone marrow, peripheral blood and inguinal lymph node. The patient was started on hydroxyurea 1 g/day and normalization of the platelet count was achieved. Possible etiopathogenic relationships between both disorders and differential diagnosis of ET and reactive thrombocytosis (RT) are discussed.

Polycythemia vera: a comprehensive review and clinical recommendations

More than a century has elapsed since the appearance of the modern descriptions of polycythemia vera (PV). During this time, much has been learned regarding disease pathogenesis and PV-associated molecular aberrations. New information has allowed amendments to traditional diagnostic criteria. Phlebotomy remains the cornerstone treatment of PV, whereas myelosuppressive agents may augment the benefit of using phlebotomy for thrombosis prevention in high-risk patients. Excessive aspirin use is contraindicated in PV, although the use of lower-dose aspirin has been shown to be safe and effective in alleviating microvascular symptoms including erythromelalgia and headaches. Recent studies have shown the utility of selective serotonin receptor antagonists for treating PV-associated pruritus. Nevertheless, many questions remain unanswered. What is the specific genetic mutation or altered molecular pathway that is causally related to the disease? In the absence of a specific molecular marker, how is a working diagnosis of PV made? What evidence supports current practice in the management of PV? This article summarizes both old and new information on PV; proposes a modern diagnostic algorithm to formulate a working diagnosis; and provides recommendations for patient management, relying whenever possible on an evidence-based approach.